Filter Comment Blacklist, to delete duplicated terms

[shadowhck]

Hi,

In Comment Blacklist, when I save terms, duplicates are not eliminated.

Would be good if the function array_unique would remove these duplicate terms.

[vancoder]

The comment blacklist is currently saved as a string, not an array, so this would be somewhat more involved than might first appear.

[SergeyBiryukov]

The solution might be similar to [22255] (explode(), array_filter() & array_unique(), implode()).

This should be applied to "Comment Moderation" list as well for consistency.

[GaVrA]

I added 23800.diff​ patch that should take care of this by explode(), array_filter(), array_unique() and finally implode() so pretty much the same way it was done in [22255].

[SergeyBiryukov]

In 28444:

Filter out empty and duplicate values in Comment Moderation and Comment Blacklist settings.

props GaVrA.
fixes #23800.